Field of the Invention
The following description relates to a wireless power transmitter and a method for transmitting power wirelessly and, more particularly, to a wireless power transmitter, which searches for a plurality of wireless power receivers using different wireless power transceiving standards, and a method for transmitting power wirelessly.
Related Art
A wireless power transmission technology is a technology of transmitting power wirelessly between a power source and an electronic device. For example, the wireless power transmission technology may provide greater mobility, convenience, and safety than a wired charging environment using the existing wired charging connector, simply by putting a mobile terminal, such as a smart phone and a tablet, on a wireless charging pad. In addition, the wireless power transmission technology is considered to replace the existing wired power transmission environment when it comes to not only wireless charging of mobile terminals, home appliances, electric automobiles, but also other various fields including medical industries, leisure, robots, and the like.
The wireless power transmission technology, which can be classified as a technology utilizing electromagnetic radiation and electromagnetic induction, is not highly efficient because of radiation loss that occurs in the air. To solve this drawback, efforts have been made to develop a technology that utilizes mainly electromagnetic induction.
Wireless power transmission technologies using electromagnetic induction are classified mainly into an inductive coupling scheme and a resonant magnetic coupling scheme.
The inductive coupling scheme is a method in which a magnetic field is radiated by a coil of a transmitter due to electromagnetic field coupling between the coil of the transmitter and a coil of a receiver and energy is transferred using current induced to the receiver. The inductive coupling scheme has an advantage of high transmission efficiency; however, its power transmission distance is limited to few mm and it is so sensitive to coil matching, so that it has a very low degree of location freedom.
The resonance magnetic coupling scheme is a method that has been proposed by Professor Marin Soljacic at MIT in 2005, the method in which energy is transferred using a phenomenon where a magnetic field is focused at both ends of a transmitter and a receiver due to a magnetic field applied with a resonant frequency between a coil of the transmitter and a coil of the receiver.
The resonance magnetic coupling scheme enables transmitting energy from few cm to few m, which is a transmission range larger than that of the inductive coupling scheme, and transmitting power using multiple devices at the same time. Thus, the resonance magnetic coupling scheme is expected as a wireless power transmission scheme that will embody real cord-free transmission.
However, there are too various standards in the wireless power transmission field. The typical standards are of Qi standard of the Wireless Power Consortium, an Alliance For Wirless Power (A4WP) standard led by Qualcomm and Samsung, a Power Matteres Alliance (PMA) standard led by Power Matteres. Under this circumstance, if a wireless power transmitter and a wireless power receiver comply with different standards, wireless power is not able to be transmitted and received between the wireless power transmitter and the wireless power receiver.